MPR-6/3-DGF Motor Protective Relay

With Directional Ground Fault Function & 3 Thermal Sensors

General

The MPR-6/3 Motor Protection Relay is a new generation of microprocessor based relay designed to protect three phase induction motors.

The MPR-6/3 incorporates two main functions.

a. Motor protection.

b. Supervision and communication.

A comprehensive protection device is required to accurately create a Thermal Model for the motor to run safely up to its limits.

This relay should protect the motor from abnormal conditions in the power supply, motor and cable faults as well as operator malfunctions.

The MPR-6/3 monitors three phase currents (true RMS line currents are measured at a sampling rate of 0.5 mSec). The MPR-6/3 monitors ground fault current (true RMS) and zero sequence voltage (3Vo), for Directional Ground Fault protection. The MPR-6/3 monitors three temperature (RTD or PTC/NTC Thermistor) inputs. Finally, the MPR-6/3 provides a comprehensive protection package.

Protection

• Too many starts
• Maximum start time
• Under current
• Load increase
• Thermal level (Overload) - Two Levels
• Over-current Jam / Stall & Short circuit – Two Levels
• Unbalanced current – Two Levels
• Directional Ground fault current
• Phase Sequence
• Temperature (3 Sensors)- RTD Pt.100 or 3 PTC/NTC Thermistor - Two Levels
• External fault 1- N.O/N.C contacts
• External fault 2 - N.O/N.C contacts

Inputs

• 3 , 5A Phase C/T's (1A is also available)
• 2 , Programmable Discrete inputs
• 1 , Residual Ground Current Input
• 1 , Open Delta Voltage Input
• Control Voltage Supply (115,230VAC 50/60Hz,110VDC)
• 3 , RTD/Thermistors

Outputs

• 1 , Alarm Relay fail safe (8A/250V)
• 1 , Trip Relay trip/trip-fail safe (8A/250V)
• 2 , Programmable (8A/250V)
• 1 , Programmable Analog Output

HMI

• 2 Lines Illuminated LCD
• 4 , LED's

Communication

• RS485 Serial Limk With Modbus / Profibus Protocol at baud rate of 1200 to 9600 bit/sec

Actual Data

• I1 , I2 , I3 Phase Currents
• T1 , T2 , T3 RTD's Temperatures
• % of Motor FLC
• Unbalance Current
• I0 Residual Current , 3V0 Zero Sequence Voltage
• Thermal Capacity
• Time to Trip
• Time to Start

Statistical Data

• Last Start Period
• Last Start Max. Current
• Last Trip Thermal Level 2
• Last Alarm Thermal Level 1
• Trip I1 , I2 , I3
• Trip I0 , 3V0
• Trip T1 , T2 , T3
• Total Run Time
• Total Number of Starts
• Total Number of Trips

Codes & Standards

Impulse :IEC 255-4 (1976) & Amend #1 (1979)

IEC 255-5 (1977)

5 kV common-mode test

5 kV transverse-mode test

Surge withstand :

Oscillatory 2.5 kV peak

Fast transient 4 kV crest voltage

In accordance with: ANSI C37.90.1 (1990), IEC 55-4 (1976)

Amend #1 (1979) Class III, IEC 255-22-2 (1988) Class III

RFI : In accordance with EMI standard ANSI C37.90.2

Technical Specification

Auxiliary Power Supply

110VDC.

Consult factory for 230VAC (165 - 260V), 115VAC (88 - 125V), (to be specify). 45 to 65Hz.

Power consumption: ≤ 10VA

Current Measurement (three currents) Method : True rms.

Range: 0.05 to 12 * phase CT Primary amps setting. Note: I1 is used to measure mains frequency. Lower (< 0.05) current may cause wrong

frequency measurement which may cause inaccurate currents and voltage measurements.

Full scale: 12 * phase CT Primary amps setting.

Accuracy : ± 1.5% , for 0.9 to 1.5 * CT Primary amps setting.

± 5% above 1.5 * CT Primary

± (3% + 0.02 * CT Primary) below 0.9 * CT Primary

Power consumption: ≤ 0.1VA per 1A at 1Amp. input, (Input impedance ≤ 100mΩ)

≤ 0.5VA per 5A at 5Amp. input, (Input impedance ≤ 20mΩ)

Directional Ground Fault 3Vo measurement Method : True RMS.

Rated input Voltage 110V / 190V.

Measurement Range: 5V to 30V. Measured with 200mA / 1.5mA ZCT.

Full scale: 30V.

Accuracy : ± 3% of full scale.

Input impedance: ≥ 50KΩ

Allowed input range: <= 220VAC (saturated, no damage)

Phase accuracy: ± 10°

Directional Ground Fault Current measurement (ZCT primary current) Method : True RMS.

Measurement Range: 0.1 to 1.0A at ZCT Primary, when measured with 200mA / 1.5mA ZCT.

0.75mA to 7.5mA at ZCT secondary.

Full scale: 1A (saturated, no damage).

Accuracy : ± 3% of full scale.

Input impedance: ≤ 10Ω

Allowed input range: <= 1A at ZCT secondary (at relay input terminals).

Phase accuracy: ± 10°

      

Thermistor Input		RTD Input
Range: 0.1 - 30KΩ.		Range: 100 - 240Ω or 0°C - 250°C
Accuracy: ± 0.1KΩ up to 5KΩ, ± 3% above 5KΩ	.	Accuracy: ± 3% of resistance.
Time delay: 2 Sec		Max wire resistance: 25Ω.

Overload Alarm and Trip Curves (both heating and cooling)

Fault time accuracy: ± 1 Second up to 10 seconds.

± 1 second ± 2% above 10 seconds.

Threshold current level : OVERLOAD PICKUP ± 1.5%.

Total Run Time

Accuracy: ±2%.

Current Unbalance Alarm and Trip

Method: Unbalance = 100 * (Imax - Imin) / Ir [%]

Where: Imax = max. of the three phase currents.

Imin = min. of the three phase currents.

Ir = larger of (Imax , Motor FLC setting).

(to prevent nuisance tripping at low current levels) Alarm

Threshold unbalance alarm level: 50% of Unbalance Current setting ± 2%.

Alarm (fixed) time delay: 5.0 ± 0.5 Sec.

Trip Curves

Threshold unbalance trip Level: Unbalance Current setting ± 2%.

Trip time accuracy: ± 1 Second up to 10 seconds. ± 1 second ± 2% above 10 seconds.

Oredering Information

Dimensions

Typical Wiring Diagram